This has been discussed at great length in the past. I am personally unaware of anything new on this front since the last discussion I took part in. The best overall deal for Canadians that I am aware of is
freephoneline.ca and
www.localphone.com is a favorite service of mine that offers Canadian DIDs.
When using Google Voice for incoming and outgoing calls the number will be a US number. It can't be made to appear as another number and it can't be forwarded to a Canadian DID. That makes Google Voice unnecessary when used with a service that provides a Canadian DID unless you want a second US presence.
Possibly someone with more recent information on Canadian ITSPs can chime in.